The production of polymers such as polyethylene from light gases requires a high purity feedstock of monomers and comonomers. Due to the small differences in boiling points between the light gases in such a feedstock, industrial production of a high purity feedstock can require the operation of multiple distillation columns, high pressures, and cryogenic temperatures. As such, the energy costs associated with feedstock purification represent a significant proportion of the total cost for the production of such polymers. Further, the infrastructure required for producing, maintaining, and recycling high purity feedstock is a significant portion of the associated capital cost.
In order to offset some of the costs and maximize production, it can be useful to reclaim and/or recycle any unreacted feedstock gases, especially the light hydrocarbon reactants, such as ethylene. Gases comprising unreacted monomers can be separated from the polymer after the polymerization reaction. The polymer is processed while the unreacted monomers are recovered from the gases that are reclaimed following the polymerization reaction. To accomplish this, the reclaimed gas streams have conventionally either been routed through a purification process or redirected through other redundant processing steps. In either case, conventional processes of recovering monomer (e.g., unreacted ethylene) have necessitated energetically unfavorable and expensive processes. Thus, there is an ongoing need for developing efficient processes for the recovery of unreacted ethylene during polyethylene production.